Hi-Def Audio on a PC?

True, graphics cards and motherboards that include high-definition multimedia interface (HDMI) outputs among their various ports and attachments are readily available. And true, you can get good audio results from installing a Blu-ray or HD-DVD player in a PC, and then using an HDMI output port to pipe the audio and video into an HDMI-equipped audio/video (A/V) receiver or a TV set.

But even then, you won't get all the different audio options you'd expect. The bottom line for system builders: The full range of audio options most likely will not be available through an HDMI port on a PC.

In this Recipe, I'll discuss the benefits of HDMI, along with its associated standards and requirements. Then I'll explain how audio is most commonly picked up and passed into a PC's HDMI port—and why it won't work with the latest high-definition multi-channel surround sound formats, such as Dolby TrueHD and DTS-HD Master Audio.

THE LOWDOWN ON HIGH-DEF MULTIMEDIA

HDMI's big draw is that it offers salvation to those whose entertainment centers have become a veritable rat's nest of cabling at the back of their A/V receivers or TV sets. A single HDMI cable can replace as many as nine cables. It does this by combining multi-channel surround-sound audio and high-definition video signals in a single compact cable with an equally compact connector.

Here's what that single HDMI cable can replace: One cable for video, which may have been a three-strand component audio or a DVI cable at the top-end of the resolution spectrum before HDMI. Eight cables for 7.1 analog audio, which uses a separate cable for each audio channel. Then add two more cables, same as before for high-end video, with optical or coaxial cables for digital audio.

As the following photo shows, when viewed side-by-side, a Type A HDMI connector (left) isn't much bigger than a Type A USB connector (right). Also, the Type A HDMI connector is electrically compatible with DVI-D:

As shown in the following diagram, HDMI pinouts are considerably more complex than USB. They include 19 leads, along with a maximum bit rate of 10.2 gigabits per second (Gbps), as opposed to the 480 megabits per second (Mbps) offered by "old-school" USB.